1. Field of the Invention
This invention relates to an image sensing apparatus having an electronic monitor and means for changing the manner in which an image sensor, etc. are driven and the manner in which power is supplied to peripheral circuits when the apparatus is in a monitor mode.
2. Description of the Prior Art
Image sensing apparatus such as electronic cameras are highly promising apparatus capable of replacing cameras using silver halide. However, they have some basic problems. The first of such problems relates to power consumption. In intermittently taking still pictures, the power consumption presents no serious problem. However, in cases where an electronic monitor is connected to or mounted on the camera, an image sensing system or a reproducing system must be continuously driven for continuous monitoring or play back. Such a requirement then presents a grave problem in connection with power consumption.
A second problem relates to the performance of the electronic monitor, such as the resolving power of the monitor. Insufficient resolving power of the monitor would bring about a spurious resolution or the like when an image signal is monitored through the same signal processing arrangement as in recording or reproduction. Furthermore, if the monitor does not possess adequate power in relation to the image sensing or recording power, that is, where the monitor is for a black-and-white signal while the image sensing or recording signal is a color signal or where the reproduction bandwidth of the monitor is narrower than the image sensing or recording bandwidth, there is a loss of electric energy and degradation of picture quality.
A third problem with the prior art apparatus lies in the relation between the resolving power of the monitor and the manner in which the image sensor is driven. Heretofore, a monitoring image signal has been obtained by driving an image sensor in the same manner as in recording or reproduction. A monitor device is thus required to have a high degree of performance. Particularly, the resolving power in the vertical direction of the monitor must be equal to that of the image sensor. The monitor arrangement of the prior art thus has resulted in a high cost.
No particular attention has been paid to these problems in the image sensing apparatus of the prior art such as electronic cameras, facsimile devices, copying machines, etc.